This application claims the priority of Korean Patent Application No. 2002-53925, filed Sep. 6, 2002 in the Korean Intellectual Property Office (KIPO), which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an apparatus for drying a semiconductor wafer, and more particularly, to an apparatus for drying a semiconductor wafer, using a cleansing vapor and deionized water, which is designed to prevent adhesion of adjacent semiconductor wafers to each other.
2. Description of the Related Art
In general, impurities formed on a semiconductor wafer during manufacture of a semiconductor chip are cleaned in a cleaning process. The cleaning process may include (a) treatment of the semiconductor wafer with a chemical solution, (b) rinsing the chemically treated semiconductor wafer with deionized water (hereinafter, xe2x80x98DIWxe2x80x99), and (c) drying the rinsed semiconductor wafer. Typically, a spin-drying method was used to dry the rinsed semiconductor wafer. However, the higher the integration of a semiconductor device, the more complicated is the surface structure of a semiconductor wafer. Accordingly, a solvent vapor drying method is employed in which the DIW is replaced by a solvent vapor of an organic material, such as an isopropyl-alcohol vapor (hereinafter, xe2x80x98IPAxe2x80x99), in the spin drying method.
FIG. 1 illustrates a method of drying a semiconductor wafer using a conventional semiconductor wafer drying apparatus that utilizes a solvent vapor drying method. Referring to FIG. 1, this semiconductor wafer solvent drying apparatus includes a chamber 110 that performs a drying process on a semiconductor wafer 100. The chamber 110 is connected to a solvent vapor storage container 130, in which a solvent solution 132 is stored, via supply line 150. The solvent vapor storage container 130 is also connected to a nitrogen gas supply pipe 134 through which a nitrogen (N2) gas is supplied from an outside source (not shown).
A wafer holder 111, on which the semiconductor 100 is positioned in the chamber 110. The wafer holder 111 is movable in the vertical direction within the chamber 110, and in turn, the semiconductor wafer 100 also can be moved in the vertical direction within the chamber 110. A waste water drain line 113 is placed below the wafer holder 111 to drain waste water remaining after evaporation of the solvent solution 132. A heater 115 is attached to the bottom of the chamber 110. The heater 115 generates heat in the chamber 110 so as to evaporate a solvent solution 132xe2x80x2 supplied in the chamber 110. Exhaust lines 117 are installed at an intermediate position B and at an upper position C of the chamber 110, so as to discharge vapor of evaporated solvent solution to the outside of the chamber 110. In addition, a filter 119 is attached to the top of the chamber 110 to filter air and the like supplied from outside the chamber 110.
A process of drying a semiconductor wafer using such a semiconductor wafer drying apparatus will now be described with reference to FIG. 1. First, the semiconductor wafer 100 cleaned with DIW is placed in the chamber 110 and is held in place by the wafer holder 111. The semiconductor wafer 100 is originally placed at a position A. When the semiconductor wafer 100 is loaded onto the wafer holder 111 in the chamber 110, the solvent solution 132 in the storage container 130 is supplied to the inside of the chamber 110 via the supply line 150.
The solvent solution 132xe2x80x2 supplied in the chamber 110 is boiled using heat generated by the heater 115. The waste water remaining after the evaporation of the solvent solution 132xe2x80x2 is discharged via the waste water drain line 113. Solvent vapor 132xe2x80x3 takes the place of the DIW associated with the surface of the semiconductor wafer 100. Next, after a certain amount of time has passed, the wafer holder 111 is moved upwardly so that the semiconductor wafer 100 is positioned at the position B in the chamber 110. Solvent vapor associated with the semiconductor wafer 100 at the position B is continuously discharged via the exhaust line 117 at the position B. Next, after a predetermined amount of time, the wafer holder 111 is moved to the position C in the chamber 110 and solvent vapor associated with the semiconductor wafer 100 is completely discharged via the exhaust line 117 at the position C. After the removal of the solvent vapor associated with the semiconductor wafer 100, the semiconductor wafer 100 is removed from the chamber 100.
The semiconductor wafer drying apparatus of FIG. 1 has its disadvantages. For example, it is difficult to precisely control the amount of solventsolution to be evaporated. If the solvent solution is evaporated under extreme conditions in the chamber 100, a great amount of carbon (C) is detected from the dried surface of the semiconductor wafer. To solve this problem, the surface of the semiconductor wafer is dried by flooding the inside of chamber 100 with DIW, and then supplying nitrogen gas and solvent vapor to the chamber in an upwardly direction of the semiconductor wafer, while discharging the DIW downwardly from the semiconductor wafer.
As the size of a semiconductor wafer increases, a drying process is performed on the semiconductor wafers using a half pitching method. The half pitching method comprises stacking the semiconductor wafers for batch processing of more than 50 sheets of semiconductor wafers of diameters of 200 mm or more. In this case, however, a reduction in the distance between semiconductor wafersis inevitable. Thus, an adverse result is produced, namely, adhesion of adjacent semiconductor wafers. The adhesion of adjacent semiconductor wafers prevents complete removal of DIW adhering to surfaces to semiconductor wafers. Water marks on the semiconductor wafers, due to incomplete removal of the DIW, causes malfunction of the semiconductor devices.
The present invention provides an apparatus and method for semiconductor wafer vapor drying wherein adhesion of adjacent semiconductor wafers is prevented during the wafer drying process.
According to an embodiment of the present invention, there is provided a semiconductor wafer drying apparatus including a bath which can contain much deionized water so that semiconductor wafers soak in the deionized water; a chamber providing a space where vapor flows over the bath; a vapor supply line supplying vapor to the internal space of the chamber; an exhaust line discharging vapor contained in the chamber to the outside of the chamber; a deionized water exhaust line discharging deionized water in the bath to the outside of the bath; a semiconductor wafer holder supporting the semiconductor wafer in the bath; and pitch guides placed at left and right sides of the semiconductor wafer, movable to a first position and a second position in a vertical direction, wherein the pitch guides are separated from the semiconductor wafer at the first position and contact the semiconductor wafer at the second position thus preventing the movement of the semiconductor wafer.
Preferably, the pitch guides can be moved to a third position where the semiconductor wafer is positioned at a distance from the semiconductor wafer holder.
Preferably, the pitch guides are connected to a motor and provided with a driving force for the vertical movement from the motor. Alternatively, the pitch guides may be connected to a piston and provided with a driving force for the vertical movement from the piston. If necessary, the vertical movements of the pitch guides may be carried out by a driving force due to lifting power of the deionized water.
Preferably a nitrogen gas and isopropyl alcohol (IPA) vapor are supplied into the chamber via the vapor supply line.
Preferably, the pitch guides are moved to the second position when an upper portion of the semiconductor wafer is exposed from the surface of the deionized water.
According to another embodiment of the present invention, there is provided a semiconductor wafer drying apparatus including a bath which can contain much deionized water so that semiconductor wafers soak in the deionized water; a chamber providing a space where vapor flows over the bath; a vapor supply line supplying vapor to the internal space of the chamber; an exhaust line discharging vapor contained in the chamber to the outside of the chamber; a deionized water exhaust line discharging deionized water in the bath to the outside of the bath; a semiconductor wafer holder supporting the semiconductor wafer in the bath; and pitch guides placed at left and right sides of the semiconductor wafer, movable to a first position and a second position in a vertical direction, wherein the pitch guides are separated from the semiconductor wafer at the first position and contact the semiconductor wafer at the second position thus preventing the movement of the semiconductor wafer.
Preferably, the pitch guides are connected to a motor and provided with a driving force for the horizontal movement from the motor. Alternatively, the pitch guides may be connected to a piston and provided with a driving force for the horizontal movement from the piston.
Preferably, nitrogen gas and IPA vapor are supplied into the chamber via the vapor supply line.
Preferably, the pitch guides are moved to the second position when an upper portion of the semiconductor wafer is exposed from the surface of the deionized water.